1. Field of the Invention
The present invention relates to a novel class of stable, nonhygroscopic compositions of potassium monopersulfate, potassium hydrogen sulfate and potassium sulfate having the formula EQU (KHSO.sub.5).sub.x.(KHSO.sub.4).sub.y.(K.sub.2 SO.sub.4).sub.z
where x+y+z=1 and x=0.48-0.64, y=0.15-0.37, and z=0.15-0.37, together with processes for making these compositions.
2. Description of the Related Art
U.S Pat. No. 2,901,319 discloses a method for preparing potassium monopersulfate by reacting a mixture of H.sub.2 SO.sub.5/ H.sub.2 SO.sub.4 in a mole ratio of 2 to 10:1 with K.sub.2 CO.sub.3, KHCO.sub.3 or KOH using a mole ratio K:H.sub.2 SO.sub.5 of from 0.6-1.2 at a temperature of from -10 to 40.degree. C. The product is washed with ethanol and dried using a vacuum.
U.S. Pat. No. 3,036,885 discloses reacting hydrogen peroxide, potassium peroxydisulfate and fuming sulfuric acid, cooling the reaction mixture, bringing the pH to 1-2 with an alkali and evaporating moisture from the resulting salts until they are dry.
U.S. Pat. No. 3,041,139 discloses preparing monopersulfate compositions containing the triple salt KHSO.sub.4.K.sub.2 SO.sub.4. 2KHSO.sub.5 by neutralizing a mixture of H.sub.2 SO.sub.5 and H.sub.2 SO.sub.4 with a basic potassium compound to form an aqueous solution which on drying contains the triple salt KHSO.sub.4: K.sub.2 SO.sub.4 :2KHSO.sub.5. The compositions of the '139 patent are shown by the closed curve ABCDA of FIG. 1. The '139 patent teaches that compositions to the right of the line CD in FIG. 1 are unstable.
British Pat. No. 979,450 discloses reacting hydrogen peroxide with concentrated sulfuric acid or oleum to form a monopersulfuric acid solution, adding potassium bisulfate or potassium sulfate to the monopersulfuric acid solution, neutralizing the resulting solution with a solution of a basic potassium compound and air drying the neutralized solution.
Canadian Pat. No. 575,441 discloses treating dried potassium monopersulfate containing mixtures with magnesium carbonate.
U.S. Pat. No. 4,579,725 discloses the preparation of a storage-stable salt primarily composed of KHSO.sub.5 and KHSO.sub.4, and optionally K.sub.2 SO.sub.4, by providing a mixture of H.sub.2 SO.sub.5 and H.sub.2 SO.sub.4 having a molar ratio of H.sub.2 SO.sub.5: H.sub.2 SO.sub.4 of 1:1 to 7:1, neutralizing the mixture with a basic potassium compound to form a reaction mixture having a molar ratio of potassium to sulfur of from 0.4:1 to 1:1, maintaining a slurry concentration in the reaction mixture of 3 to 40% of substantially cavity-free crystals containing KHSO5, maintaining the slurry at about 15-35.degree. C., and separating the reaction mixture into a substantially liquid-free crystalline cake and a mother liquor stream at about 15-35.degree. C.